Electrical signaling system



April 14, 1942 T. B. D. TERRONI i ELECTRICAL SIGNALING SYSTEM Filed Fb. e, 1959 3 Sheets-Sheet l INVENTOR TESEO BRUNO DANTE TERRON/ YZ ATTORNEY April 14, 1942. T. B. D. TERRoNl ELECTRICAL S IGNALING SYSTEM 5 Sheets-Sheet 2 INVENTOR ATTORNEY April 14, 1942. T. B. D. TERRONI ELECTRICAL SIGNALING SYSTEM 3 Sheets-Sheet C5 Filed Feb. 6, 1959 INVENTOR TE SEU BRU/V0 DANTE TERRO/V/ Patented Apr. 14, 1942 UNITED STATES PATENT OFFICE ELECTRICAL SIGNALING SYSTEM Delaware Application February 6, 1939, Serial No. 254,826 In Great Britain February 9, 1933 15 Claims.

The present invention relates to electrical signaling systems and is more particularly concernedl with systems in which speech or other supervisory signals and also signaling currents are transmitted over a signaling channel in the form of high frequency alternating currents or so-called carrier current.

The invention has particular application to a protective arrangement for high Voltage power lines in which the occurrence of a fault in one section of the system causes a signal to be transmitted to prevent the operation of the circuit breakers of adjacent sections in order that these adjacent sections are not disconnected from the system unnecessarily in the course oi isolating the faulty section. It should be understood however that the invention is not limited to such an arrangement but may have other applications. The general object of the invention is to provide a signaling system whereby the operation of power line protective gear may be improved and rendered more reliable.

According to one feature ofthe invention in.

an electrical signaling system suitable for the protection of power lines including an arrangement involving the transmission of carrier current over a signaling channel, a signal is arranged to start suddenly by the use of an oscillator valve which is normally prevented from operating by a relay contact which is opened when a signal is to be transmitted.

According to another feature of the invention in an electrical signaling system suitable for the protection of power lines including an arrangement involving the transmission of carrier current over a signaling channel, a signal is arranged to stop suddenly by the use of an oscillator valve the operation of which is arrested by the opening of a relay contact when a signal is to be terminated.

A further feature of the invention is that in an electrical signaling system for the protection of power lines by an arrangement involving the transmission of carrier current over the power conductors and having arrangements for transmitting speech over the same circuit, by the use of carrier current of a different frequency, the equipment for initiating the transmission of the signaling frequency serves also to effect the cessation of the transmission of the carrier current for speech.

The invention will be better understood from the following description of one embodiment taken in conjunction with the accompanying drawings comprising Figs. 1-4. Fig. 1 shows schematically the arrangement of the various circuits at one end of a section of the power line, and Figs. 2 and 3 when placed together with Fig. 3 below Fig. 2 show in detail the circuits located at the other end of the section. Fig. 4 shows how Figs. 1 3 should be placed with respect to one another to properly understand the invention.

Referring now more particularly to the drawings, a high voltage power line is indicated by the three phase conductors R', Y and B extending across the top of Figs. 1 and 2. This power line is divided into a number of sections or' which A-B is one and B-C is another. As is common, protective gear is located at both stations A and B for protecting the A-B section of the line and like equipment is located at both stations B and C for protecting the B-C section; thus it will be seen that station B, for example, has two sets of equipment, one of which is for the A-B section while the other is for the B-C section. Only one of these sets has been shown at station B, however, this being the one associated with the A-B section, and, similarly, but one set has been shown at station A. Examining the latter station, it will be seen that this has three phase fault relays, one or more of which operate whenever a fault develops in the line, and a directional relay of the polyphase watt meter type which is arbitrarily adjusted to operate only under conditions accompanying the occurrence of a fault in the A-B section or to the 'right thereof, as, for example, in the B-C section. Station B has three corresponding phase fault relays, IPf, 2Pf and 3Pf; the directional relay DR at station B is adjusted to operate its contacts only under conditions accompanying a fault in the A-B section or to the left thereof. The carrier circuits are associated with the power line over a transformer TRI at station A and a transformer TR2 at station B, the secondary windings being connected to two of the phase conductors of the line over suitable protection gear which will be referred to in greater detail subsequently.

At station A the signal transmitter SITI and speech transmitter SPTI have a common output to the primary of the transformer TRI which is connected in parallel with the input to the signal receiver SIRI over the band pass filter FBI and with the input to the speech receiver SPR! over the high pass lter FHI. A similar arrangement is employed at station B except that the input to the speech receiver SPRZ is by way of a low pass filter FLZ. Tuned carrier traps are provided as shown to prevent carrier currents impressed upon any section of the line from passing to the adjacent sections. These, of course, do not interfere with the transmission of power over the line.

The general method of protecting the A-B section is as follows: Assuming that a fault develops in the B-C section of the line, this will be detected at stations A and B by the operation of a phase fault relay at each. The operation of a contact of this relay causes a lock-in signal of frequency say fs to be impressed upon the A-B section by both the signal transmitters SIT! and SITZ at stations A and B. At station A the signal is received by the signal receiver SIRi and serves to maintain operated a relay which prevents the closure vof a circuit for the tripping coil of the A--B section circuitbreaker. A similar operation occurs at station B. In addition it will be noted that there is a local feed back circuit from each signal transmitter such as SIT! to the signal receiver such as SIRI to ensure that the circuitbreakers at stations A and B are both locked-in immediately the signal is transmitted to the line.

The directional relays at stations A and B now function to give an indication of the direction in which the fault current is flowing. At station B the directional relay which is associated with the A-B section will not be operated since, as Y has been pointed out, this is set to operate only when the fault is to the left of station B. At station A however the directional relay asso ciated with the A-B section will operate. The

operation of the directional relay at station A causes the transmission of the lock-in signal from that station to cease but it continues to be impressed upon the line at station B because the directional relay thereat is not operated. This signal prevents tripping of the circuit breakers for isolating the A--B section of the line.

The circuits remain in this condition until the circuit-breakers at station B serving the B-C section trip on the fault to isolate the B-C section. The phase fault relays thereupon de-energise and restore their contacts at stations A and B whereupon the lock-in signal transmission from station B ceases.

If a fault `occurs on the A-B section, the phase fault relays operate and as before the lockein signal is transmitted from both stations. In this case however the directional relays at both stations A and B operate and signal transmission will then cease in order to allow the circuit breakers at stations A and B associated with the A-B section to trip to isolate the section.

With regard to the speech channels, a carrier frequency of JAB say is assigned to the channel for transmission from A to B and a carrier frequency of BA is assigned to the channel for transmission from B to A. The frequencies fAB, fBA and fs are conveniently of the order of 100 kilocycles per second.

The method of operation having been described generally. a more detailed description will now be given.

Referring to Figs. 2 and 3 it will be seen that, as mentioned above, three circuits are connected in parallel with the lowei` winding of the transformer TR2. These three circuits are the signal receiver SIR2, the combined signal and speech transmitters SITZ and SPTZ respectively and the speech receiver SPRZ. The signal receiver circuit SIR2 includes the band pass filter FB2 which is arrange to have a narrow pass range extending on either side of the lock-in signaling frequency of fs and to produce infinite attenuation of the two speech carrier frequencies AB and feA. The output from the filter is applied over the transformer TRS to an amplifying valve Vi the anode circuit of which includes the primary winding of a step-up transformer TRA, the secondary winding of which includes a gas-filled discharge tube, preferably a neon tube NT. The neon tube is connected over a resistance RI to the grid of the pentode detector valve V2 so that when a lock-in signal is incoming to the signal receiver a high positive potential is applied to the grid of the detector valve. The anode circuit of the detector valve V2 includes a supervisory relay SR and a winding LRE of the lock-in relay LR. The second pair of winding LR2 of the lock-in relay LR are normally energised from the tripping battery of 1li) volts over series-connected contacts Ipfi, Zpfi and 3gofl of the phase fault relays. The armature Zr of the lock-in relay is normally maintained in the position shown by the energisation of winding LRZ while in its other position a circuit is closed over parallel-connected contacts Ipf2, 2pf2 and 3pf2 of the phase fault relays and contact dri of the directional relay for the tripping coil TC of the circuit-breaker associated at station B with section A-B.

The circuit of the signal transmitter SITZ comprises the pentode valve V3 which in consequence of the connection between the anode circuit and the grid including the tuning circuit L, C is arranged to act as an oscillator. It will be noted that the current supply to the anode circuit of the oscillator is normally shunted over contacts Ipf3, 2pf3 and 3pf3, and test contacts te. In addition the cathode circuit of the oscillator is normally closed over contact dr2 of the directional relay DR associated with the A-B section at station B. The output from the oscillator is taken over the transformer TRS of which the tuning inductance L forms the primary winding, and by way of resistances R2 and R3 to the grids of two pentodes V4 and V5 ar- `ranged in push-pull. The output from the two pentodes V4 and V5 is taken over the transformer TR to the transformer TR2 and thence to the line.

The transmitter T and the receiver R are connected respectively over switchhook contacts SWI and SW2 and condensers Ci and C2 to the righthand windings of the transformers TR1 and TRS. The other ends of the transformers are connected together over a normally open contact of relay BR and positive potential is connected to these ends over contacts ipfd, 2pf4 and Spfll. It will be noted also that a direct electrical connection is provided at D between the two windings of transformer TR'I. The lefthand winding of transformer TR1 supplies the input to the speech transmitter SPTZ while the the two push-pull valves V4 and V5.

The input to the speech receiver SPRZ passes over a low pass filter FL2 the output from which is applied over the transformer TRIO to the grid of three electrode valve V8 in the anode circuit of which is located a signaling relay CR. The AC output from the valve is applied over condensers C4, and C5 to the left-hand winding of transformer TRS and thence to the receiver R.

It will be understood that the equipment at station A is precisely similar to that at station B except that the valve corresponding to V'! generates oscillations having a frequency of fins and the lter corresponding to FLz is a high pass filter.

The operation of these circuits is as follows: Assume that the attendant at station B desires to speak to the attendant at station A and for this purpose removes his receiver thereby closing the switch-hook contacts SW! and SW2 and opening the switch-hook contacts SW3. The closing of swtich-hook contacts SW! completes an obvious circuit for relay BR which at Contact br applies an ope-rating positive potential to the cathodes of the valves V6 and Vl. Valve V1 thereupon commences to generate oscillations of a frequency of fBA and these are transmitted over the transformer TR9, amplified by the valves V4 and V5 and transmitted over the transformers TRS and TR2 to station A.. At station A the carrier wave is applied over the transformer TRI and the high pass iilter FH! to the detector valve in the speech receiver SPR! corresponding to the valve V8 in the speech receiver SPRZ (Fig. 3). The direct current component of the anode current causes the operation of the relay corresponding to relay CR which closes a circuit over the switchhook contacts corresponding to contacts SW3 for a bell similar to B. Upon the reply of the attendant at station A the switchhook contacts SW3 are opened to interrupt the bell circuit and switchhook contacts SW! and SW2 are closed with the same result as at station B. Conversation can now take place between the two stations.

If during conversation a fault occurs, for ini` the local circuit of winding LRZ of the lock-in relay at station B and similar for station A. At the same time contacts IpfS open the shunt across the anode supply for the oscillating valve V3 to enable this valve to generate the lock-in signal. It will be appreciated that resistance R4 is inserted between the positive terminal of the high potential source and the phase fault relay contacts in order to prevent a direct shortcircuit being placed across the supply. Contact Ipfd removes the potential applied to the cathodes of the Valves V6 and V'i at station B and the corresponding contacts perform a similar function at station A in order to interrupt immediately the transmission of speech between the two stations. in addition the closing of contact IN2 prepares a circuit for the trip coil TC at station B and a corresponding circuit is prepared at station A. The lock-in signal generated by the valve V3 are transmitted over transformer TR2 to station A and also over the band pass filter FB2 at station B. The signal is amplified by the valve V! and the output therefrom causes i tional relay at station A does.

the neon tube NT to strike and apply a high positive potential to the grid of the detector valve V2. This arrangement ensures that the detector valve passes saturation current. A further advantage of employing a neon tube in this manner is that by completing the circuit of' the tube through the very low impedance of the supply circuit no condensers need be used for completing the alternating current circuit of the neon tube and no delay in operation is introduced by such condenser-resistance combinations.

The rectified current in the anode circuit causes the operation of the supervisory relay SR. The purpose of the supervisory relay which is marginal in operation is to give a remote indication as to the level of the incoming signal if signal current is transmitted for test purposes for instance by operating the contacts tc. In addition the anode current causes the energisation of winding LR! of the lock-in relay LR. Due to the energisation of winding LR! the armature of the lock-in relay is maintained in the position shown in the drawings and thus the circuit for the trip coil TC is held open. A similar result occurs at the station A.

The next step in the operation of the system concerns the directional relays DR and as pointed out above, the directional relay at station B does not operate at this time, but the direc- Consequently at station A the contact corresponding to contact dr! is closed to prepare a further point in the circuit of the trip coil and at the contact correspending to Contact r2 the cathode circuit of v" the lock-in signal oscillator is opened so that this valve ceases to generate oscillations. It will however be understood that the lock-in relay at station A is still maintained operated due to the signal transmitted from station B, so that the circuit of the trip coil at station A is held open in spite of the closing of contacts corresponding to dr! and lpf. The circuits remain in this condition until the fault is cleared whereupon the phase fault relays and the directional relays will revert to their initial condition so that the shunt is again placed on the oscillator V3 and the circuits prepared for the trip coils at stations A and B are opened. Conversation may now be resumed between the stations.

With regard to the operation oi the system on a fault developing on section A-B, in this case the directional relays at both stations A and B operate so that 'the lock-in signal is immediately terminated at station B as well as at station A. The lock-in relays at stations A and B thus de-energise and circuits are closed for the tripping coils which operate the circuit-breakers to open the power line and isolate the A-B section.

In connection with the operation of the loch-in relay it will be appreciated that it is very necessary that winding LR! of this relay should operate quickly upon the occurrence of a fault since at the same time the locally energised winding LR2 is disconnected. For this to be effected reliably it is desirable that the lock-in signal should be generated substantially immediately a fault occurs, or alternatively' that winding LRE should be made slow-to-release by suitable known methods so that it does not release until winding LR! is energised. The latter alternative has the disadvantage that the relay then releases slowly on true tripping conditions and the arrangement according to the invention whereby the oscillator V3 starts up substantially immediately a fault develops is therefore preferable. Various proposals have been made for ensuring the quick starting up of the lock-in signal oscillator but the arrangement shown in which the anode supply is normally shunted by closed contacts which are opened on the occurrence of a fault is found to be most advantageous. The opening of one of these contacts causes the high tension to be applied to the valve suddenly and as the opening time is short since it comprises only the time required for a moving spring to leave its back Contact, the oscillations are applied rapidly to the line.

It is also desirable that relay LR should release quickly so as to enable a fault on section A--B to be cleared as rapidly as possible by the closing of the trip coil circuit. It is therefore necessary that the lock-in signal oscillator should be stopped in the minimum time when the necessary conditions exist. accordingto the invention by inserting the break contact civ-2 of the directional relay .in the cathode circuit of the oscillator V3.

It will be understood that while the arrangements for short-circuiting the oscillator V3 and for disconnecting the cathode potential to the valves V and Vl have been shown as different contacts of the same phase fault relay, it is possible as pointed out above, that the same contacts shall effect the two operations.

Furthermore the position shown for the contact 117-2 is not the only possible one as this contact could be made to serve the same purpose if included in the anode circuit or in the high tension supply circuit to the valve. stood also that the invention is equally applicable to a carrier signaling system employing an earth return.

It should be mentioned that in actual practice it is usual to employ two sets of phase fault relays, one with a light and the other with a heavy setting. The latter are only brought into operation on the release of relay LR and these relays would carry the contacts Ipf, 2pf2, and 3pf2. On the other hand the relays with the light setting which carry the remainder of the pf contacts operate immediately a fault develops as has been described above.

The protective circuits located between the high frequency circuits and the power line preferably include non-linear resistance material in order to afford protection against instantaneous rapid rise of voltage due to surges. Such resistance material is progressive in its action and cuts out the build-up time associated with a protector of the spark gap type. Preferably the non-linear resistance material employed comprises a mixture of silicon carbide with carbon and/or tungsten or molybdenum which is agglomerated under pressure and subsequently baked. In the arrangement shown for the connection to the transformer TRI two units of resistance material PI and P2 are connected across the line and earthed at the junction point. Series inductances NDI and ND2 are connected in each line on the side of the resistance units nearest the high frequency circuits, followed by a shunt inductance NDS with the centre point earthed. The two lines are then led to a cable extending to the high frequency circuits, the cable being protected by neon tubes Nl and N2. Similarly the transformer TR2 is protected by the use of units of resistance material P3 and P4, inductances NDd, NDS and NDS and neon tubes N3 and N4.

This has been achieved It will be under- I I claim:

1. In a signaling system, a line comprising a plurality of line sections, two oscillators associated with a particular one of said line sections, only one of said oscillators normally impressing alternating current on said particular line section, and means operated responsive to an abnormal condition on a different one of said line sections thereupon to prevent alternating current from being impressed upon said particular line section by said one oscillator during the existence of said condition and to cause the other of said oscillators to impress alternating current on said particular line section for the duration of said condition.

2. In a signaling system, a line comprising a plurality of line sections, two oscillators associated with one of said line sections, only one of said oscillators normally impressing alternating current upon said one line section, means operated whenever a fault occurs on any section of said line to disable said one oscillator and to cause the other oscillator to impress alternating current upon said one line section, and means operated only if said fault is within said one line section for thereafter disabling said other oscillator.

3. In a signaling system, a line divided into a plurality of line sections, two oscillators each adapted to impress an alternating current signal upon one section of said line, means normally preventing one of said oscillators from impressing its signal upon said one line section, means operated responsive to the occurrence of a fault on any section of said line to render said last means ineffective and to prevent the other of said oscillators from impressing its signal upon said one line section, and means operated thereafter only if said fault is within said one line section to again prevent said one oscillator from impressing its signal upon said one line section.

4. In a signaling system, a line comprising a plurality of line sections, means for producing two high frequency Waves, means for impressing said waves upon a particular one of said line sections, and means operated responsive to an abnormal condition on a different one of said line sections for preventing one of said Waves from being impressed upon said particular line section and causing the other of said waves to be impressed upon said particular line section throughout the existence of said abnormal condition.

5. In a signaling system, a line, a plurality of different locations at which faults may occur on said line, means for producing two high frequency waves, means for impressing said Waves upon said line, and means operated responsive to the occurrence of a fault at one location on said line to prevent a particular one of said waves from being impressed upon said line and operated responsive to the occurrence of a fault at another location on said line to prevent both of said waves from being impressed upon said line.

6. In a signaling system, a line comprising a plurality of line sections, a high frequency transmitter normally impressing a wave of a particular frequency upon a particular one of said line sections, a normally inoperative high frequency transmitter capable of generating a Wave of a frequency different from said particularl frequency, and means for automatically disabling said first transmitter when a fault occurs on a section of said line other than said particular line section and thereupon rendering said second transmitter effective to impress upon said particular line section a Wave of said different frequency.

7. In a signaling system, a line, means for superimposing a plurality of signaling paths upon said line, means for transmitting signals over each of said paths, and means responsive to an abnormal condition on said line to disable all of said superimposed paths and to impress upon said line a special signal indicative of the presence of said condition.

8. In a signaling system, a line divided into a plurality of line sections, means for superimposing three signaling paths upon one of said sections of said line, means operated Whenever a fault occurs in any of said line sections to automatically disable a particular two of said paths, and means operated only if said fault is in said one section to disable the remaining one of said paths.

9. In a carrier Wave communicating system, a line, means for superimposing upon said line a communication channel, means for transmitting intelligence over said channel, means operated responsive to an abnormal condition on said line and effective to disable said first means, and means controlled by said last means upon said operation thereof to impress upon said line a special signal indicative of said condition.

l0. In a carrier Wave communicating system, the combination with a line comprising a plurality of line sections, of means for superimposing upon one section of said line a communication channel for transmission of intelligence over that section, means operated automatically whenever a fault occurs in any of said line sec tions for disabling said communication channel, means effective if said fault is in a section other than said one section for superimposing upon said one section a control channel, and means for isolating said one section from the other sections responsive to the occurrence of said fault if said control channel is not superimposed upon said one section, said control channel effective, When superimposed upon said one section, to prevent the operation of the means for isolating said one section.

11. The combination with a line comprising a plurality of line sections, of means for producing two high frequency Waves, means for impressing said waves upon said line, means operated responsive to the occurrence of a fault in one section of the line for preventing one of said waves from being impressed upon said line and causing the other of said Waves to be impressed upon a section of said line other than said one section, and means for isolating said other section responsive to the occurrence of a fault in any of said line sections if said other Wave is not impressed upon said other line section, said other Wave effective, when impressed upon said other Lil) section, to prevent the operation of the means for isolating said other section.

l2. In combination With a power line comprising a plurality of line sections and having circuit breakers for isolating any section upon occurrence of a fault therein, a carrier wave communication systemoperating over said line, means for disabling said system responsive to a fault occurring in one section of said line, a special signal control oscillator rendered eiective responsive to the occurrence of said fault to impress a signal upon another section of said line, means for operating the circuit breakers for iso* lating said other section responsive to the occurrence of a fault in any of said line sections if said signal is not impressed upon said other section, said signal effective, if impressed upon said other section, to disable said last means.

13. In combination with a power line comprising a plurality of line sections each having circuit breakers for isolating that section, a carrier Wave communication system normally operating over one section of said line, a normally disabled oscillator for transmitting a special control signal over said one section, fault responsive means subject-to faults occurring in any of said line sections and effective when a fault occurs in said one section to trip the circuit breakers to isolate said one section from the other sections of said line, means controlled by said last means responsive to a fault occurring in a section of said line other than said one section for disabling said carrier wave communication system and rendering said oscillator operative to transmit said special control signal over said one section, and means responsive to said special control signal for preventing the circuit 1breakers of said one section from tripping.

14. In a signaling system, a line comprising a plurality of line sections, a high frequency transmitter normally impressing a wave of a particular frequency upon one section of said line, a normally inoperative high frequency transmitter, means for automatically disabling said first transmitter and causing said second transmitter to impress upon said one line section a wave of a different frequency Whenever a fault occurs on said line Within any of said line sections, and means then operated antomatically to disable said second transmitter only if the fault is within said one line section.

15. In a carrier Wave communicating system, a line, means for superimposing upon said line a plurality of communication channels, means for transmitting intelligence over each of said channels, means operated responsive to an abnormal condition on said line and effective to disable said first means, and means controlled by said last means upon said operation thereof to impress upon said line a special signal indicative of said abnormal condition.

TESEO BRUNO DANTE TERRONI. 

